The present invention is directed to bicycles and, more particularly, to an apparatus for adjusting a position of a bicycle control device.
Some modern bicycles have various electrical control devices used to control the bicycle transmission, the bicycle suspension, and so on. An example of an electrical control device used to control front and rear bicycle derailleurs is shown in U.S. Pat. No. 5,059,158. The control device shown in that reference controls the front and rear derailleurs using an automatic gear shift mode, a manual gear shift mode, and a calibration mode. When the control device is in the automatic gear shift mode, the cadence (i.e., crank RPM) is determined from the bicycle speed and the gear ratio, and the front and rear derailleurs are controlled by moving each derailleur to a desired sprocket position so that the cadence will fall within a preset range. When the control device is in the manual gear shift mode, an upshift or downshift alert signal is displayed if the cadence falls outside a preset range. The rider then may manually command the control device to perform an appropriate upshift or downshift using an electrical switch.
The calibration mode is used when the control unit is first set up, such as when the bicycle is manufactured, in order to record the proper derailleur position for each sprocket. The calibration mode also is used to fine-tune the derailleur position when the actual derailleur position for a particular sprocket deviates from the proper position. For example, the actual derailleur position may become offset from the desired position due to stretching of the gear shift cable, the shape of the frame, or the derailleur mounting method. In calibration mode, the sprocket position for a derailleur can be adjusted in the upshift and downshift directions by operating corresponding upshift and downshift switches on the handlebar. Unfortunately, such a conventional derailleur control device requires the derailleur position to be calibrated separately for each sprocket. Thus, the calibration procedure can be cumbersome, particularly with a rear derailleur that operates with a large number of sprockets.